AUSTIN — U.S. District Judge Sam Sparks on Friday blocked Texas from enforcing a rule requiring fetal remains from abortions and miscarriages to be buried or cremated.

Sparks said the rules "likely are unconstitutionally vague and impose an undue burden on the right to an abortion." He issued a preliminary injunction Friday that will stay in place until the case is decided. A trial date will be set in about a month.

Texas Attorney General Ken Paxton said he plans to appeal the decision and continue to fight to honor "the dignity of the unborn."

"Today's ruling, however, reaffirms that the abortion lobby has grown so extreme that it will reject any and every regulation no matter how sensible," Paxton said in a prepared statement. "Indeed, no longer content with merely ending the life of the unborn, the radical left now objects to even the humane treatment of fetal remains."

Abortion providers in Texas sued the state over the rule last year, arguing that it imposes a religious ritual on women, does not benefit public health and could lead clinics to close as few vendors are willing to perform cremation and burial services for tissue from abortions.

"Anti-abortion attacks cannot and will not slow us down," Amy Hagstrom-Miller, president of Whole Woman's Health and the lead plaintiff in the case, said in a prepared statement. "It is so important that our resiliency continues to blaze a path so that people in all communities are inspired to stand up and continue to fight back against political interference that attempts to regulate our lives."

Sparks heard testimony from abortion providers, funeral directors and the Texas Conference of Catholic Bishops over a two-day hearing earlier this month, at the end of which he delayed implementation of the rules until Friday.

The existing rules allow for the burial of fetal tissue but also allow it to be disposed of the same way as other human tissue or pathological waste — incinerated, ground or disinfected and deposited in a sanitary landfill or sewer system. Most facilities that offer abortion services contract with vendors and opt for incineration.

Lawyers for the state defended the proposed burial rules in court this month and said they ensure that fetal remains are treated with dignity, the same reason Gov. Greg Abbott has expressed support for the measure.

But Sparks wrote that by "seeking to respect life and the dignity of the unborn regardless of gestational age," the state is establishing the beginning of human life as conception, which potentially undermines the equal protection clause of the 14th Amendment.

Sparks also wrote that the state expressed a number of "contradictory positions" over whether fetal tissue is to be treated as human remains or as pathological waste.

During proceedings, lawyers for the state argued that fetal tissue is not the same as human remains and therefore did not violate a state law that allows cremated ashes to be scattered on private property with the owner's consent. State officials said it would be expressly prohibited to scatter ashes in a landfill.

Sparks also said that the rules were politically motivated and do not "have any benefit at all to health" because they were announced within days of the U.S. Supreme Court striking down key provisions of House Bill 2, a 2013 state law regulating abortion providers. Attorneys with the state said the rules were in consideration long before the high court's decision, in which Whole Woman's Health was also the plaintiff.

Sparks addressed this in his injunction, writing that the state drafted the rules "before the ink on the Supreme Court's opinion in Whole Woman's Health was dry."

Abortion providers told Sparks they know of only one vendor in the state who is willing to handle cremation and burial of the tissue from clinics, which could put the company at risk of becoming a target for anti-abortion advocates.

Providers said they were also concerned about the cost of following the rules, as they don't state whether health providers or a woman would be required to cover the cost of disposal. A group of Texas Catholic bishops has offered to pay for burials required by the rules.

Doctors in court this month expressed concerns that the rules put women in a difficult position, as many providers said patients rarely ask to have the fetal tissue buried. Karen Swenson, an OB-GYN in Austin, said the the rules "might cause some distress for some patients."

Some Texas women started protesting the rule by mailing Abbott used feminine hygiene products with instructions: "Bury this!"

The case in front of Sparks is over a series of amendments to administrative code, but Rep. Byron Cook, R-Corsicana, has filed a bill that would turn the requirement into a law.

"Today's ruling is disappointing; however, the two-day court hearing provided us with essential input to ensure we pass good, constitutionally sound public policy," Cook said in a prepared statement, pledging to change such "antiquated, abhorrent practices."